1. Field of the Invention
The present invention relates to a method for producing resinous particles, a precursor, resinous particles, a toner, a developer, a toner container, a process cartridge, an image forming method, and an image forming apparatus.
2. Description of the Related Art
Among the conventional methods for producing a toner, a pulverization method is a method for producing a toner by kneading toner materials containing a binder resin, a coloring agent such as a pigment, wax and the like, finely dispersing the wax in the binder resin, and then pulverizing. The toner produced in the pulverization method may be referred as a pulverization toner, hereinafter. The pulverization toner generally has the wax content of only 3% by weight to 6% by weight due to the production process thereof and handling of the toner.
On the other hand, a chemical method, which uses aggregations or the like, is a method for producing a toner encapsulating wax by using the characteristics such that particles are built up to form the toner. The toner produced in the chemical method is referred as a chemical toner, hereinafter. The chemical toner is capable of encapsulating a large amount (e.g. 10% by weight or more) of the wax compared to the pulverization toner, does not require the application of oil on a fixing roller and the like, and is suitable for an oil-free toner which enables a low temperature fixing. It has been known a technology of the chemical toner which maintains the offset temperature high and improves the low temperature fixing property by dispersing the fine particles of the wax in an area adjacent to the surface of the toner.
The pulverization method requires a lot of know-how for controlling the dispersion state of the wax, and the control thereof is not easy. Related to the fixing performance, it is not preferable that the dispersion state of the wax is entirely even, and the dispersion state of the wax requires being uneven at a certain degree so that the toner has a wide range of an appropriate fixing temperature, namely a large deference between the temperature range of the low temperature offset and the temperature range of high temperature offset. Specifically, the condition where the wax is finely dispersed in the binder resin is more preferable than the condition where the wax is compatible with the binder resin. However, if the wax is unevenly dispersed, other substances may be dispersed unevenly. Moreover, this may cause a fusion during the process of pulverization. Furthermore, the wax content may becomes uneven between the collected toner as a result of the classification and the toner substances of coarse or fine particles, and thus the recycling of the coarse or fine particles becomes difficult. Therefore, it is generally difficult to provide the pulverization toner with all of a wide fixing temperature range, the uniform physical property of the toner, and easiness of the production at the same time.
Moreover, the toner containing the wax produced in accordance with the pulverization method has a problem in durability. Generally speaking, the region of the wax or an interface between the region of the wax and the region of the binder resin is weak compared to the region of the binder resin, and thus the region of the wax or the interface between the region of the wax and the region of the binder resin is highly likely broken at the time of pulverization. Namely, the pulverization toner is highly likely to have the wax on the surface thereof, and such the wax present on the surface of the toner becomes a factor for staining a photoconductor, or staining a carrier in a two-component developer.
On the other hand, the chemical toner has a large content of the wax, and a high potential for flexibility in the structural design, but the know-how for the structural design is not yet sufficient, and it is not economical, since most of the production equipments and know-how of the pulverization toner cannot be used in the production of the chemical toner. Moreover, depending on the production method, the varieties of the binder resin for use may be limited, a large volume of the effluent treatment may be required, and a large amount of the organic solvent may be required to use. For example, only polyester resins can be used in a suspension polymerization method, and a large amount of the organic solvent is required in a dissolution suspension method. Moreover, for example, 10 times by weight of washing water is required for removing (washing) a surfactant of the like used at the time of a reaction, emulsification, liquid dispersion, or the like from the surface of the toner at the time of producing the toner in these polymerization methods.
As a method for producing a toner other than the pulverization method and the chemical method, there has been disclosed a spray dry method wherein particles are atomized by blowing a resin melted solution by using a compressed air or the like (refer to Japanese Patent Application Laid-Open (JP-A) No. 2005-258394). However, further modification or improvement needs to be done for a means and method for controlling the structure of the toner.
As a technology positioned between the pulverization method and the spray dry method, there have been known a spinning pulverization method wherein a resin is spun and then pulverized (refer to JP-A No. 2004-332130), and a method for producing composite particles by using a composite spinning technology (refer to JP-A No. 2005-187773). In this method, it may be possible to produced a toner encapsulating wax, which is difficult to be produced in accordance with the pulverizing method, for example by spinning the binder resin while supplying a compound of a low melting point into the binder resin by means of a composite spinning nozzle (e.g., a core-in-sheath spinning nozzle, and a multiple-tube spinning nozzle), and then pulverizing the resin fibers and classifying the same. However, this method has problems such that the construction and control of the nozzle becomes complicated.
Moreover, there has been proposed a method for producing a toner encapsulating wax in the similar manner to the one disclosed in JP-A No. 2005-187773 (refer to JP-A No. 2006-285198). This method utilizes a shape or inner characteristics of a nozzle. For example, an encapsulating structure is formed by using a double tube nozzle, and supplying the binder resin from the outer tube and the wax from the inner tube. Alternatively, an encapsulating structure is formed in a nozzle by using the nozzle which has an inner surface having higher compatibility to the binder resin than wax. The thus obtained fibrous product is pulverized to thereby yield a toner. However, in the case where the multiple tube nozzle is used, there is a problem such that the construction of the device becomes complicated. Moreover, no specific descriptions about the inner surface having higher compatibility to the binder resin than the wax are disclosed.
As a method for controlling the state of the wax present in the toner, there has been disclosed a method for forming a thin layer after melt-kneading the wax and the binder resin (refer to Japanese Patent (JP-B) No. 3409100). In accordance with this method, the dispersion state of the wax becomes excellent by thinning the kneaded product containing the wax, and then quenching.